J. Compos. Sci., Volume 9, Issue 5 (May 2025) – 46 articles

This study investigates the influence of crack width on the time to chloride-induced corrosion initiation in reinforced concrete (RC) bridge decks, incorporating climate change projections through the year 2100 under IPCC scenarios (RCP2.6 and RCP8.5). A probabilistic modelling approach using Monte Carlo simulations (MCSs) was applied to assess corrosion initiation across a range of environmental and structural conditions, including normal and high-performance concrete (HPC), varying concrete cover depths, and the use of supplementary cementing materials (SCMs). The results indicate that increasing the crack width significantly accelerates chloride ingress, reducing the time to corrosion initiation by up to 41% compared with that under uncracked conditions. HPC demonstrated superior durability, delaying corrosion initiation by nearly twice as long as normal concrete under identical chloride exposure. Elevated temperatures projected under high-emission scenarios further reduce service life by increasing chloride diffusion rates. Polynomial regression models were developed to relate crack width and concrete cover to corrosion initiation time, offering practical tools for durability-based design and service life prediction. These findings highlight the importance of enhanced crack control, climate-adaptive material selection, and updated durability standards to improve the resilience of RC bridge infrastructure in the face of climate change. Full article

The development of lightweight construction is of crucial importance for the development of sustainable technologies and for the reduction in carbon dioxide emissions, especially in the automotive industry. This study aims to address the challenges associated with manufacturing plant fibre-based polymer composites. The investigation focused on two novel formulations of bio-based unsaturated polyester resins, assessing their viability as a matrix in plant fibre-reinforced composites within the context of automotive applications. The study addresses the challenges related to the preparation and processing of the system, leading to the necessity of diluting the resin with (hydroxymethyl)methacrylate (HEMA) to achieve an applicable viscosity. Two different flax fibre textiles, in the form of a short fibre mat and a woven fabric, were used as reinforcement. The composite panels were manufactured using the vacuum-assisted resin infusion (VARI) process. The most efficacious material combination, comprising Bcomp^® ampliTex™ 5040 and STRUKTOL^® POLYVERTEC^® 3831, with viscosity modified by 39% HEMA, exhibited a consistent fibre volume fraction of 40% and a glass transition temperature of 70 °C. In addition, the mechanical behaviour in the 0°-direction demonstrated tensile strength and modulus values of approximately 99 MPa and 9 GPa, respectively, accompanied by an elongation at break of 2%. The flexural modulus was found to be 7 GPa, and the flexural strength 94 MPa. Full article

Phosphorus contamination in water bodies is a major contributor to eutrophication, leading to algal overgrowth, oxygen depletion, and ecological imbalance. Conventional treatment methods, including chemical precipitation and synthetic adsorbents, are often limited by high operational costs, low biodegradability, and secondary pollutant generation. In this study, a cationic starch was synthesized through free radical graft polymerization of 3-methacrylamoylaminopropyl trimethyl ammonium chloride (MAPTAC) onto corn starch. The modified polymer exhibited a high degree of substitution (DS = 1.24), indicating successful functionalization with quaternary ammonium groups. Theoretical calculations using zDensity Functional Theory (DFT) at the B3LYP/6-311+G(d,p) level revealed a decrease in chemical hardness (from 0.10442 eV to 0.04386 eV) and a lower ionization potential (from 0.24911 eV to 0.15611 eV) in the modified starch, indicating enhanced electronic reactivity. HOMO-LUMO analysis and molecular electrostatic potential (MEP) maps confirmed increased electron-accepting capacity and the formation of new electrophilic sites. Experimentally, the cationic starch showed stable zeta potential values averaging +15.3 mV across pH 5.0–10.0, outperforming aluminum sulfate (Alum), which reversed its charge above pH 7.5. In coagulation-flocculation trials, the modified starch achieved 87% total suspended solids (TSS) removal at a low coagulant-to-biomass ratio of 0.0601 (w/w) using Scenedesmus obliquus, and 78% TSS removal in real wastewater at a 1.5:1 ratio. Additionally, it removed 30% of total phosphorus (TP) under environmentally benign conditions, comparable to Alum but with lower chemical input. The integration of computational and experimental approaches demonstrates that MAPTAC-modified starch is an efficient, eco-friendly, and low-cost alternative for nutrient and solids removal in wastewater treatment. Full article

In recent years, there has been increasing interest in new materials such as ceramic matrix composites (CMCs) for power generation and aerospace propulsion applications through hydrogen combustion. This study employed a deep artificial neural network (DANN) model to predict the ablation performance of CMCs in the hydrogen torch test (HTT). The study was conducted in three phases to increase the accuracy of the model’s predictions. Initially, to predict the thermal behavior of ceramic composites, two linear machine learning models were used known as Lasso and Ridge regression. In the second step, four decision tree-based ensemble machine learning models, namely random forest, gradient boosting regression, extreme gradient boosting regression, and extra tree regression, were used to improve the prediction accuracy metrics, including root mean square error (RMSE), mean absolute error (MAE), correlation coefficient (R² score), and mean absolute percentage error (MAPE), relative to the previously introduced linear models. Finally, to forecast the thermal stability of CMCs with time, an optimized DANN model with two hidden layers having rectified linear unit activation function was developed. The data collection procedure involved preparing CMCs with continuous Yttria-Stabilized Zirconia (YSZ) fibers and silicon carbide (SiC) matrix using a polymer infiltration and pyrolysis (PIP) technique. The samples were exposed to a hydrogen flame at a high heat flux of 183 W/cm² for a duration of 10 min. A good agreement between the DANN model’s predictions and experimental data with an R² score of 0.9671, RMSE of 16.45, an MAE of 14.07, and an MAPE of 3.92% confirmed the acceptability of the developed neural network model in this study. Full article

Staining removal is an issue of interest in dentistry. Current treatments deal with staining removal on enamel, while few studies concentrate on resin composites. The aim of the current study is to evaluate the efficacy in staining removal of an ozonated gel on dental composites. The study sample consisted of 40 specimens of restorative composites: 20 specimens were stained for 1 day in tea solution (tea group) and 20 specimens were stained for 1 day in physiological solution (NaCl group). Both the tea and NaCl groups underwent the experimental treatment as follows: five specimens underwent ozonized gel application, five specimens underwent an ozonized spray, five specimens underwent an application of olive oil, and five specimens were not treated. A colorimetric evaluation was performed with a spectrophotometer, using CIEDE2000 data elaboration at the baseline (T0), after staining (T1), and after staining removal (T2). In the T0–T1 time frame, significantly different color changes (ΔE₀₀) were found between tea groups and NaCl groups (p < 0.05), except for control groups (p > 0.05). After staining removal in the T1–T2 period, no significant differences in ΔE₀₀ were found (p > 0.05). Higher values were found for groups treated with ozonized gel, denoting a stain removal effect. The groups treated with olive oil, instead, exhibited higher ΔE₀₀ values, showing a greater staining effect. In conclusion, the ozonized gel tested showed staining removal activity on restorative resin composites. Future clinical applications are required to validate the in vitro results obtained. Full article

This study presents the fabrication and characterization of magnetically active textiles using cotton fibers impregnated with suspensions of pumpkin seed oil, carbonyl iron microparticles, and propolis microparticles. The textiles were utilized to manufacture planar capacitors, enabling an investigation of the effects of static magnetic fields and the introduced microparticles on the components of complex dielectric permittivity. The results reveal that the dielectric properties of the fabricated textiles are highly sensitive to the applied magnetic field intensity, the frequency of the alternating electric field, and the composition of the impregnating suspension. The experimental findings suggest that the dielectric loss and permittivity can be finely tuned by adjusting the magnetic flux density and the proportion of propolis microparticles. The multifunctional nature of these magnetically responsive textiles, combined with the bioactive properties of the incorporated natural components, opens promising pathways for applications in smart textiles, biomedical devices, and sensor technologies. Full article

In the field of dentistry, achieving a natural look in dental restorations is crucial. This relies significantly on the ability of composite materials to mimic the optical characteristics of natural teeth, particularly their fluorescence. Fluorescence plays a vital role in giving teeth their lifelike appearance and varies widely among different materials, impacting their long-term performance in clinical settings. This study aims to assess and compare the fluorescence properties of four advanced composite restorative materials against natural dental enamel through both laboratory and clinical evaluations. The research involved an in vitro examination of 50 samples categorized into five groups, with one control group (natural dental enamel) and four experimental groups (G-Aenial, GC Essentia, Brilliant Flo, and Omnichroma). Fluorescence intensity was measured both visually and through photographic techniques immediately after application and again after 30 days. Furthermore, a randomized clinical trial was conducted with 40 participants to evaluate the in vivo fluorescence of these composites used in cervical restorations. Statistical analyses were performed using the Kruskal–Wallis test and Wilcoxon signed rank test. The analysis revealed significant differences in fluorescence levels across all groups (p < 0.05). Among the composites tested, Omnichroma exhibited the closest resemblance to natural enamel fluorescence at both baseline and after 30 days, with p-values of 0.01 for in vitro and 0.02 for in vivo assessments. Notably, all composite materials, except for the control group (natural enamel), showed a decrease in fluorescence over time, with G-Aenial and GC Essentia experiencing more pronounced reductions compared to Omnichroma (p = 0.03). Omnichroma was found to most effectively replicate the fluorescence of natural enamel, leading to better esthetic results. However, it is important to note that all composite materials demonstrated a decline in fluorescence over time, indicating a need for ongoing development to enhance their durability. Full article

This study investigates the impact of widely used mineral fillers in self-compacting concrete compositions applied in vibration-free reinforced concrete production technology, as a means of enhancing rheological characteristics and cost-effectiveness. Three distinct types of mineral fillers, including the well-studied fillers microsilica and metakaolin, as well as the lesser-explored filler Kazakhstani natural opal-chalcedony opoka, are examined in this research. In addition to the evaluation of conventional rheological and performance properties of concretes containing these fillers, the internal processes within the cement–filler matrix are analyzed. This includes X-ray phase analysis and microstructural examination of cement hydration products in combination with a superplasticizer and each of the three minerals. The findings confirm the potential for optimizing the rheological parameters of the concrete mixture by substituting up to 15% of the cement with mineral fillers, achieving optimal viscosity and workability. It is established that compositions with the addition of microsilica and metakaolin have a more homogeneous structure, mainly represented by low-basicity calcium hydrosilicates of the CSH(B) type, along with an increase in compressive strength of up to 10%. The addition of these mineral fillers to C30/35 strength class self-compacting concrete resulted in improved frost resistance up to F300, a reduction in volumetric water absorption by up to 30%, and a decrease in shrinkage deformations by 32%. The developed SCC compositions have successfully passed production testing and are recommended for implementation in the operational processes of reinforced concrete product manufacturing plants. Full article

The impact of acidic beverages on dental restorative materials, such as composites and glass ionomers, is critical in conservative dentistry. Exposure to an acidic environment can lead to the degradation of these materials, affecting their durability and clinical effectiveness. We aimed to examine the effect of sports drink exposure on the surface roughness of composite and glass ionomer materials. This systematic review was conducted based on the records published from 1 January 2005 to 31 December 2024, according to PRISMA statement guidelines, using the databases PubMed, Scopus, Web of Science, and Embase. Following the inclusion and exclusion criteria, 10 studies were included in this review and 6 in the meta-analysis. Meta-analysis demonstrated a statistically significant increase in surface roughness (Ra parameter) for glass ionomer materials after immersion in sports drinks for one week and one month. No such significant differences were observed for composite materials. Despite the systematic review, the degree of material degradation presented by in vitro studies cannot be directly extrapolated to oral conditions due to factors such as the buffering capacity of saliva or irregular exposure times to sports drinks. Full article

This study investigates the mechanical performance of basalt fiber-reinforced polymer (BFRP) laminates as a suitable alternative to conventional glass fiber-reinforced composites for marine applications. The laminates were produced by varying the main process parameters: the fiber type was either glass or basalt; the resin material was either polyester or vinylester; the fiber orientation in selected layers was set to either 0°/90°, or to ±45° by rotating the woven fabrics during lay-up, and finally the manufacturing technique was either hand lay-up or vacuum infusion. Three-point flexural tests with different spans were conducted to evaluate the flexural behavior and fracture mechanisms. The best-performing configuration, based on glass fibers and vacuum infusion, achieved a maximum flexural strength of about 500 MPa, while basalt-based laminates reached values of up to 400 MPa. Basalt laminates exhibited the highest flexural modulus, with values exceeding 24 GPa. An increase in span length from 120 mm to 220 mm resulted in a reduction in flexural strength of approximately 6–18% depending on the laminate configuration, highlighting the influence of loading conditions on mechanical behavior. The effect of the manufacturing processes was also evaluated using an analysis of variance. This showed that fiber type, manufacturing method, and span significantly influenced the mechanical performance. Full article

An electrochemically active and promising binary composite that is made up of titanium-based MXene (Ti₃C₂T_x) and rGO is developed to simultaneously detect the Cd²⁺ and Cu²⁺, in water. XRD, FTIR, Raman, XPS, FESEM, elemental mapping, and EDX analysis affirmed the successful formation of the Ti₃C₂T_x-rGO composite. The produced Ti₃C₂T_x-rGO electrode exhibited a homogeneous rGO sheet covering the Ti₃C₂T_x MXene plates with all the detailed Ti2p, C1s, and O1s XPS peaks. The high-performance Ti₃C₂T_x-rGO composite was successfully tested for the Cd²⁺ and Cu²⁺ ions via differential pulse voltammetry (DPV), altering the pH, concentration, and the real water sample’s quality. The electrochemical performances revealed that the proposed Ti₃C₂T_x-rGO composite depicted excellent detection and quantification limits (LOD and LOQ) for both Cd²⁺ (LOD = 0.31 nM, LOQ = 1.02 nM) and Cu²⁺ (LOD = 0.18 nM, LOQ = 0.62 nM) ions, where the result is highly comparable with the reported literature. The Ti₃C₂T_x-rGO was proven highly sensitive towards Cd²⁺ (0.345 μMμA⁻¹) and Cu²⁺ (0.575 μMμA⁻¹) with great repeatability and reproducibility properties. The Ti₃C₂T_x-rGO electrode also exhibited excellent stability over four weeks with a retention of 97.86% and 98.01% for Cd²⁺ and Cu²⁺, respectively. This simple modification of Ti₃C₂T_x with rGO can potentially be advantageous in the development of highly sensitive electrochemical sensors for the simultaneous detection of heavy metal ions. Full article

Drop-on-demand (DoD) printing is an additive manufacturing technique that utilizes functional inks containing nanoparticles (NPs) to fabricate electronic circuits or devices on a variety of substrates. One of the most promising applications for such technology is the aerospace industry, due to the capability of this method to fabricate custom low-weight geometric films. This work evaluates the performance of a gold (Au) nanoparticle (NP)-based film printed on a ceramic substrate for avionics applications, following the environmental temperature guidance of the Radio Technical Commission for Aeronautics (RTCA) DO-160. Experimental results show that the Au films, printed on alumina substrates, successfully survived the environmental temperature procedures for airborne equipment. The thermal coefficient of resistance (TCR) of the films was measured to be $2.7\times {10}^{-3} {°\mathrm{C}}^{-1}.$ Full article

In recent decades, the application of composite materials in aerostructures has significantly increased, with modern commercial aircraft progressively replacing aluminum alloys with composite components. This shift is exemplified by comparing the material compositions of the Boeing 777 and the Boeing 787 (Dreamliner). The Boeing 777 incorporates approximately 50% aluminum alloy and 12% composite materials, whereas the Dreamliner reverses this ratio, utilizing around 50% composites and 12% aluminum alloy. While metals remain advantageous due to their availability and ease of machining, composites offer greater potential for property tailoring to meet specific performance requirements. They also provide superior strength-to-weight ratios and enhanced resistance to corrosion and fatigue. To ensure the reliability of composites in aerospace applications, comprehensive testing under various loading conditions, particularly impact, is essential. Impacts were performed on quasi-isotropic (QIT) carbon-fiber reinforced epoxy panels with stainless steel, round-nosed and flat-ended impactors with rubber discs of 1-, 1.5- and 2 mm thickness, adhered to the flat-ended impactor to simulate the transition between hard and soft impact loading conditions. QIT composite panels were tested in this research employing similar lay-ups often being implemented in aircraft wings and other structures. The rubber discs were applied in the flat-ended impactor case but not for the round-nosed impactor due to the limited adhesion between the rubber and the rounded stainless-steel surface. Impact energies of 7.5, 15 and 30 J were investigated, and the performance of the panels was evaluated using force-time and force-displacement data alongside post-impact ultrasonic C-scan imaging to assess the damaged area. Damage was observed at all three energy values for the round-nosed impacts but only at the highest impact energy when using the flat-ended impactor, leading to the hardness study with adhered rubber discs being performed at 30 J. The most noticeable difference with the addition of rubber discs was the reduction in the damage in the plies nearest the top (impacted) surface. This suggests that the rubber reduces the severity of the impact, but increasing the thickness of the rubber from 1 to 2 mm does not notably increase this effect. Indentation clearly plays a significant role in promoting delamination at low-impact energies for the round-nosed impactors. Full article

In this research paper, the ±45 biaxially oriented woven flax and its hybrid flax/carbon composite laminates are manufactured by the vacuum bag technique using vinyl ester as the resin binder and the samples are characterized to evaluate their tensile, flexural and impact properties. Combining natural fibers with conventional materials typically creates a hybrid composite that shows optimal mechanical properties with partial sustainability. The flax/carbon variant exhibited superior tensile strength values of 383.88 MPa and 32.60 GPa, which are about 3.5 and 2.7 times higher than the flax composites, their flexural strengths are around 415.57 MPa and 25.02 GPa, respectively, and they have an impact resistance of 12.67 J. Full article

Magnetoelectric composites enable strain-mediated coupling between magnetic and electric fields, supporting applications in sensors, actuators, and tunable devices. This study presents a finite element modeling framework for simulating the direct magnetoelectric effect in core–shell and layered nanocomposites fabricated by material jetting (inkjet printing). The model incorporates nonlinear magnetostrictive behavior of cobalt ferrite nanoparticles and size-dependent piezoelectric properties of barium titanate, allowing efficient simulation of complex interfacial strain transfer. Results show a strong dependence of coupling on field orientation, particle arrangement, and interfacial geometry. Simulations of printed droplet geometries, including coffee ring droplet morphologies, reveal enhanced performance through increased surface area and directional alignment. These findings highlight the potential of material jetting for customizable, high-performance magnetoelectric devices and provide a foundation for simulation-guided design. Full article

The growing demand for passenger comfort and environmental protection, as well as reducing fuel consumption and exhaust emissions, drives the search for new, high-performance materials. Composite leaf springs, applied as part of elastic suspension systems and with the advantages of being strong and lightweight, with a high load-carrying capacity, are a possible method with which to achieve those goals. In this study, an epoxy thermoset was blended with 10–50 wt.% polysulfide rubber and reinforced with 10 wt.% alumina powder. The characteristics of the copolymer composite blend were studied by performing ASTM mechanical tests, including tensile strength, impact strength, hardness, and damping ratio tests. The experimental outcomes showed that increasing the proportion of polysulfide rubber caused a reduction in the maximum tensile strength, modulus at fracture, natural as well as damped frequency, and hardness, whereas a significant improvement was observed in impact strength, logarithmic decrement, and the damping ratio. Reinforcement with alumina powder caused a meaningful increase in the maximum tensile strength and natural frequency, with a good improvement in deformation strength. Impact strength and the damping ratio were maximized when alumina powder was increasingly added. This increase was contrary to what occurred for the hardness, which decreased upon reinforcement. Statistical methods, altering the design of the experiments, and linear regression were used to optimize the composite mixture for manufacturing leaf springs. Finally, the model was validated using analysis of variance and probability plots (normal distribution). The regression equations of tensile and impact strength, hardness, and damping ratio test results proved composite suitability for the application of leaf springs under representative loading and operating conditions. Finite element analysis of the composite material was performed using SolidWorks Simulation 22 Mechanical software. ANSYS 2022 R1 was used to study the mechanical properties of the leaf spring model fabricated from the proposed composite material. The finite element analysis results showed a significant reduction in the weight of leaf springs, with very good mechanical properties, including the tensile and impact strength, hardness, and damping ratio, when using the proposed copolymer-reinforced composite material. Full article

In both fundamental and applied scientific exploration, nanostructured protective materials have garnered substantial interest owing to their multifaceted utilization in the fields of medicine, pharmaceuticals, and electronics, among others. This study investigated the evolution of cutting-edge materials for electromagnetic radiation attenuation, with a specific emphasis on the incorporation of superparamagnetic magnetite nanoparticles, Fe₃O₄, into composite systems. The nanoparticles were generated through chemical condensation, meticulously adjusting the proportions of iron salts, specifically FeSO₄·7H₂O and FeCl₃·6H₂O, in conjunction with a 25% aqueous solution of ammonia, NH₄OH·H₂O. This study examined the intricate details of the crystalline structure, the precise composition of phases, and the intricate physicochemical attributes of these synthesized Fe₃O₄ nanoparticles. The analysis was conducted employing a suite of advanced techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive analysis (EDAX). The key findings of this research suggest that the magnetic nanoparticles generated through chemical condensation have an average size between 10 and 11 nm. This size was determined using BET surface area measurements, which were precise to within 0.1 nm. Moreover, this study demonstrated that incorporating superparamagnetic nanoparticles into composite materials significantly reduces microwave radiation. In particular, an optimal concentration of 0.25% by weight leads to a maximum decrease of 21.7 dB in cement specimens measuring 10 mm in thickness. Moreover, a critical threshold concentration of 0.5 weight percent is established, beyond which the interactions of nanoparticles inhibit the process of remagnetization. These investigations demonstrate that it is feasible to pursue a route towards the development of highly effective electromagnetic shielding materials tailored to specific requirements for diverse applications. Full article

This article discusses the current problem of industrial waste disposal and its use in the production of building materials, which corresponds to the global concept of sustainable development. Attention is mainly paid to the development of a gruntosilicate composite (concrete) based on a mineral slag binder using drilling sludge from the mining industry, ashes from thermal power plants and electrothermophosphoric slag. Physico-chemical studies of man-made raw materials have been carried out, including analysis of chemical and mineralogical composition, granulometric characteristics, radiation safety and other parameters. It has been established that drilling mud, thermal power plant ash and electrothermophosphoric slag meet the requirements for use in building materials and belong to non-hazardous waste. The optimal ratios of the components in the composition of gruntosilicate concrete have been experimentally determined. The highest compressive strength (3.0–3.5 MPa) is achieved with a drilling mud content of 15–23% and a mineral slag binder of 10–20%. It is shown that the introduction of these wastes improves the structure of the material, reduces shrinkage deformations and ensures compliance with the requirements of road surfaces of the II–III classes. The use of industrial waste in construction will reduce the cost of raw materials by approximately 10–30%, reduce the environmental burden and solve the problem of waste disposal. The results of the study demonstrate the prospects of creating a waste-processing industry capable of processing up to 40% of industrial waste into building materials. Full article

Polypyrrole (PPy)-doped bismuth calcium manganite (BCM) nanocomposites were synthesized by chemical polymerization. The amorphous nature of the polypyrrole and the monoclinic crystal structure of the BCM particles (35–65 nm) were confirmed by various microstructural, X-ray powder, and spectroscopy techniques. The DC conductivity analysis via the correlated barrier-hopping (CBH) model and Mott’s variable-range hopping (MVRH) model showed that the nanocomposites exhibited ionic conduction. Activation energies, evaluated from the Arrhenius plots, showed that PPy/BCM-30 (30 wt.% of BCM) had the minimum value of 0.09 eV, indicating maximum conductivity and normal NTCR behavior, with resistance decreasing with temperature. The CBH model described the conduction process, and the AC conductivity measurements indicated that the conductivity was frequency-independent at lower frequencies but became dispersive and frequency-dependent at higher frequencies, conforming to Jonscher’s power law. The study revealed that the transport of electrical charge in the material followed the correlated barrier-hopping (CBH) model. These results demonstrate how promising PPy/BCM nanocomposites are for energy storage, sensors, and electronic materials. Full article

In this study, a novel lignin-based magnetic composite with a shell-and-core structure and high saturated magnetic strength has been developed for the efficient removal of Pb(II) from wastewater. The adsorbent was fabricated through the introduction of silica–amino groups and a cross-linking complex with lignin, utilizing Fe-Fe₂O₃ as a magnetic source. The paramagnetic characteristics enabled its rapid separation from the aqueous solution within merely 15 s. Batch adsorption experiments demonstrated that the adsorbents could reach equilibrium for Pb(II) adsorption within 30 min. When the concentration of Pb(II) is in the low range of 0 to 200 mg/L, the removal rate of Pb(II) approaches 100%, and the theoretical maximum adsorption capacity is as high as 384.2 mg/g. The mechanism analysis indicated that the adsorption process was primarily characterized as monolayer chemisorption. Notably, the resultant bio-composites demonstrated a high level of stability even after eight consecutive adsorption and desorption cycles, with the removal rate of Pb(II) still reaching 82.3%. This work outlines a novel approach for designing highly efficient lignin-derived adsorbents toward wastewater treatment. Full article

This study investigates, for the first time, the effects of polypropylene, steel, glass, and synthetic fibers on the mechanical and environmental properties of high-performance concrete (HPC) incorporating zeolite as a substitute for aggregates and cement. A series of tests, including compressive strength (load-displacement), slump, specific gravity, and water absorption percentage, were conducted to evaluate the performance of the composite materials. Additionally, the IMPACT2002+ method was employed to assess the environmental impacts of the different fiber types. Furthermore, a life cycle costing (LCC) analysis was performed to evaluate the economic feasibility of using these fibers in sustainable HPC applications. The findings reveal that the incorporation of steel fibers results in a notable improvement in compressive strength, achieving 92 MPa compared to 85 MPa for fiber-free samples. Additionally, modified synthetic macro fibers exhibited the second-highest compressive strength, at 83 MPa, while also demonstrating the lowest environmental impact among the tested fibers, characterized by the lowest cost index and minimal carbon dioxide emissions. Full article

Thermogravimetric analysis (TGA) is a technique used to investigate the thermal characteristics of materials by observing fluctuations in sample mass with changes in temperature. Amid the increasing worldwide focus on sustainable materials, biocomposites have become popular for their eco-friendly characteristics. Thermal stability is a crucial factor in determining the performance of biocomposites. The present research improved thermal properties by incorporating wheat straw residual filler into an epoxy resin matrix after various chemical treatments of wheat straw fibers, such as alkali (NaOH) or a combination of silane and alkali treatments. Machine learning (ML) analysis performed in WEKA 3.0 was conducted on thermal data derived from the thermogravimetric measurements of the biocomposites. This research took into account several factors, such as filler loading, single or dual chemical treatment, and temperature, to forecast the thermal-degradation behavior during combustion. Sixteen distinct regression models were used to predict the TGA curves. The K-Nearest Neighbor (KNN) classifier outperformed the other 15 models by achieving an R-squared value of 0.9999, indicating remarkable prediction skills. The strong correlation between the experimental data and the anticipated values confirmed the accuracy of the ML computations. Full article

Natural fibers have become increasingly popular owing to their affordability, environmental friendliness, and renewability. Owing to their abundance and low density, they have gained attention in their use as reinforcements in polymer composites. However, untreated natural fiber composites have several disadvantages, including higher water absorption, low-to-moderate mechanical properties, and challenges with fiber-to-matrix adhesion. To address these drawbacks, various approaches have been employed, such as the chemical treatment of natural fibers, fiber hybridization, and the incorporation of nanoparticles/fillers. Chemical treatment enhances the interfacial bonding with the polymer matrix by different mechanisms. Hybridization enhances the mechanical properties of composites by leveraging the advantages of individual fibers. The incorporation of nanoparticles enhances the mechanical properties and various other properties due to a significant increase in interfacial interaction, which is a result of the increased surface area of nanoparticles. Full article

This study presents the fabrication and characterization of hybrid magneto-responsive composites (hMRCs), composed of recyclable components: magnetite microparticles (MMPs) as fillers, lard as a natural binding matrix, and cotton fabric for structural reinforcement. MMPs are obtained by in-house plasma-synthesis, a sustainable, efficient, and highly tunable method for producing high-performance MMPs. hMRCs are integrated into flat capacitors, and their electrical capacitance (C), resistance (R), dielectric permittivity (${ϵ}^{\prime }$), and electrical conductivity ($\sigma$) are investigated under a static magnetic field, uniform force field, and an alternating electric field. The experimental results reveal that the electrical properties of hMRCs are dependent on the volume fractions of MMPs and microfibers in the fabric, as well as the applied magnetic flux density (B) and compression forces (F). C shows an increase with both B and F, while R decreases due to improved conductive pathways formed by alignment of MMPs. $\sigma$ is found to be highly tunable, with increases of up to 300% under combined field effects. In the same conditions, C increases up to 75%, and R decreases up to 80%. Thus, by employing plasma-synthesized MMPs, and commercially available recyclable lard and cotton fabrics, this study demonstrates an eco-friendly, low-cost approach to designing multifunctional smart materials. The tunable electrical properties of hMRCs open new possibilities for adaptive sensors, energy storage devices, and magnetoelectric transducers. Full article

Additive manufacturing (AM) has the potential to revolutionize the fabrication of continuous carbon fiber-reinforced polymer composites (CCFRPCs). Among AM techniques, direct ink writing (DIW) with ultraviolet (UV) curable resin shows promise for creating CCFRPCs with high manufacturing speed, high fiber volume fraction, and low energy consumption. However, issues such as incomplete curing and weak interfacial bonding, particularly in dense fiber bundles, limit the mechanical performance. This study addressed these challenges using pre-impregnated systems (PISs), which is a process developed to impregnate dry fiber bundles with partially cured resin before being used for DIW printing, to enhance resin-fiber adhesion and fiber–fiber bonding within fiber bundles. By optimizing resin viscosity and curing conditions in the PIS process, samples treated by PIS achieved improved mechanical properties. Tensile and bending tests revealed significant performance gains over non-PIS treated samples, with tensile stiffness increasing by at least 39% and bending stiffness by 45% in 3K fiber bundles. Tensile samples with thicker fiber bundles (6K and 12K) exhibited similar improvements. On the other hand, while all samples exhibit enhanced mechanical properties under bending deformation, the improvement of flexural stiffness and strength with thicker fiber bundles is shown to be less significant than those with 3K fiber bundles. Overall, composites made with PIS-treated fibers can enhance mechanical performance compared with those made with non-PIS-treated fibers, offering the scaling capability of printing thicker fiber bundles to reduce processing time while maintaining improved properties. It emphasizes the importance of refining the pre-processing strategies of large continuous fiber bundles in the AM process to achieve optimal mechanical properties. Full article

Waterborne polyurethane (WPU) coatings have gained significant attention in the industry due to their low environmental impact and excellent properties. Furthermore, the UV-curing system reduces energy costs and enhances curing efficiency. Hence, exploring the UV-curable WPU system is essential for advancing the next generation of coatings. In this study, a 2K WPU system was developed by functionalizing isocyanate-terminated polyurethane with thiol and vinyl groups. The coating was cured under UV light through a thiol-ene click reaction, and the effects of photoinitiator content on the coating performance were investigated. The feasibility of sunlight curing for this WPU coating was also assessed. The results showed that while photoinitiator content had a slight impact on UV-cured WPU coatings, it significantly affected sunlight-cured WPU. Also, with the appropriate photoinitiator content, sunlight-cured WPU could achieve comparable performance to UV-curable ones. Full article

This experimental study produced recycled sand–silica fume–hair fiber concrete to enhance concrete sustainability. Recycled sand and silica fume can be used to address the environmental issues caused by excessive river sand mining and the carbon footprint of the concrete industry. In addition, waste hair fibers (0.5–2%) were introduced to enhance the properties of newly developed concrete mixes. The absolute volume method was employed for four newly developed sustainable concrete mixes. A 100 mm slump was set as a structural concrete requirement, which was maintained by adding 0.5%, 1%, 1.4%, 1.9%, and 2.6% of the admixture by weight of the cement to the proposed mixes. The compressive strength, splitting tensile strength, and density of the hardened concrete mixtures were estimated. The study results show that combining optimized 10% silica fume with 0.5–2% hair fibers enhanced the properties of the newly developed sustainable mixes. The slump threshold was met when 1.5% of hair fibers were mixed with 10% silica fume, 50% manufactured sand, and 50% recycled sand. However, the splitting tensile strengths of the mixes with 1.5% and 2.0% hair fibers were found to be almost the same at 5.62 MPa and 5.65 MPa, respectively. The bulk density of the mixes increased with increasing percentages of hair fibers. Furthermore, in the mixes with 1.5% and 2.0% hair fibers, the bulk density was very similar at 2.708 g/cm³ and 2.792 g/cm³, respectively. Thus, it can be concluded from the study results that concrete containing recycled sand, silica fume, and hair fibers in optimal percentages is acceptable as structural concrete. Full article

This study numerically investigated free vibration characteristics of functionally graded material (FGM) beams on Winkler–Pasternak three-parameter elastic foundations using the modified generalized differential quadrature (MGDQ) method. To compare the effects of different beam theories on the predicted frequency responses, an nth order generalized beam theory was employed to establish the governing equations of the system’s dynamic model within the Hamilton framework. As a pioneering effort, a MATLAB (version 2021a) computational program implementing the MGDQ method was developed to obtain the free vibration responses of foundation-supported FGM beams. Parametric analyses were conducted through numerical simulations to systematically examine the influences of various factors, including beam theories, damping coefficients, foundation stiffness parameters, boundary conditions, gradient indices, and span-to-thickness ratios, on the natural frequencies and damping ratios of FGM beams. The findings provide an essential theoretical foundation for dynamic characteristic analysis and functional design of foundation-supported FGM beam structures. Full article

This work shows a three-dimensional (3D) layerwise model for static and free vibration analyses of functionally graded piezomagnetic materials (FGPM) spherical shell structures where magnetic and elastic fields are completely coupled. The 3D magneto-elastic governing equations for spherical shells are made of the three equations of equilibrium in three-dimensional form and the three-dimensional divergence equation for the magnetic induction. Governing equations are written in the orthogonal mixed curvilinear reference system ($\alpha$, $\beta$, z) allowing the analysis of several curved and flat geometries (plates, cylindrical shells and spherical shells) thanks to proper considerations of the radii of curvature. The static cases, actuator and sensor configurations and free vibration investigations are proposed. The resolution method uses the imposition of the Navier’s harmonic forms in the two in-plane directions and the exponential matrix methodology in the transverse normal direction. Single-layered and multilayered simply-supported FGPM structures have been investigated. In order to understand the behavior of FGPM structures, numerical values and trends along the thickness direction for displacements, stresses, magnetic potential, magnetic induction and free vibration modes are proposed. In the results section, a first assessment phase is proposed to demonstrate the validity of the formulation and to fix proper values for the convergence of results. Therefore, a new benchmark section is presented. Different cases are proposed for several material configurations, load boundary conditions and geometries. The possible effects involved in this problem (magneto-elastic coupling and effects related to embedded materials and thickness values of the layers) are discussed in depth for each thickness ratio. The innovative feature proposed in the present paper is the exact 3D study of magneto-elastic coupling effects in FGPM plates and shells for static and free vibration analyses by means of a unique and general formulation. Full article

Synthetic plastic impacts the environment due to its slow degradation and the generation of microplastics, driving the development of bioplastics. This study evaluated the use of bagasse fiber combined with corn and potato starch to improve the physical and mechanical properties of bioplastics. Five bioplastic mixtures (Am1 to Am5) were prepared with corn starch, glycerin, acetic acid, maleic anhydride, and agave bagasse. Am1 was prepared without bagasse, and the others were prepared with different amounts of bagasse (0, 10, 30, 50, and 70 g). Bioplastics made from potato starch (Ap1 to Ap5) were also produced under the same conditions and were assessed using the thermogravimetric (TGA) and scanning electron microscopy (SEM) tests. Analysis of variance showed significant differences (p < 0.001) in the moisture, Young’s modulus, and stress of the bioplastics. The corn-based bioplastics exhibited lower moisture values (7.26% and 5.51%) compared to the potato-based ones (9.68% to 8.89%). Young’s modulus and stress increased in the corn-based (Am5 = 4.59 MPa) and potato-based (Ap5 = 3.53 MPa) bioplastics with higher amounts of bagasse. Furthermore, TGA and SEM revealed the surface morphology and the effects of processing, and based on their results, it was found that agave bagasse improved the mechanical and thermal properties of bioplastics, especially corn-based ones, suggesting its potential as a material with a lower environmental impact. Full article